Transmission of information via fiber optic cables has been shown to offer several advantages; among them an extremely wide bandwidth communication channel offering substantial immunity to electrical interference.
As fiber optic technology has grown in sophistication, cable manufacturers have developed variations in cable configurations. The variations are intended to enhance the reliability and performance of the systems but have also introduced complications when it is found necessary to form a splice between two optical fibers. The quality of the splice, both in terms of the separation between the cables and their axial alignment, is especially important in that it directly affects the efficiency of optical transmission between the cables.
Numerous techniques have been developed in an attempt to effectuate a splice as desired. For example, U.S. Pat. No. 4,078,910 to Dalgoutte describes a method of joining cables by inserting the two ends of the cables into opposite ends of a glass sleeve having a bore that provides a clearance fit around the perimeters of the cables. The sleeve is heated at the abutment of the cable ends and, because it has a lower melting point than the cables, collapses around the cable. Subsequently, a length of heat-shrinkable tubing may be placed over the sleeve in order to enhance the mechanical strength of the splice. U.S. Pat. No. 3,883,353 to Cohen et al. is directed to a photolitographic technique for shaping the opposing ends of the fiber optic cable. One end is formed to provide a protruding portion; conversely, the other end is formed to provide a complementary indented portion. The result is a male-to-female connection at the fiber ends.
An alternate approach is described in U.S. Pat. No. 4,056,305 to McCartney et al. That patent is directed to a fiber optic connector comprising a deformable elastomeric material having axially aligned bore. Dual sets of at least three rods are mounted within the bore. Because the rods have substantially identical diameters, they form a tricuspid aperture. The dimensions of the aperture are such that insertion of the cables causes the elastomeric material to be compressed, thereby exerting a radial force on the rods. It is asserted that in this manner the cables become precisely laterally aligned.
U.S. Pat. No. 3,734,594 to Trambarulo describes an optical fiber splice having a deformable annular core disposed between a pair of metallic pressure plates. The two fibers to be spliced are inserted into opposite ends of the core and a longitudinal force is applied to the plates. This causes the core to deform radially, thereby simultaneously aligning and mechanically securing the fibers.
A similar technique is described in U.S. Pat. No. 4,178,067 to Johnson et al. according to which a cylindrical body of heat recoverable matter such as polyethylene, polystyrene or polyvinyl chloride, is heated, axially stretched, then cooled in order to reduce the diameter of the material. The resultant diametrical reduction operates to confine two previously inserted optical waveguides. The material is confined within a cylinderical sleeve comprised of a dimensionally stable material such as metal, glass or any stable polymeric material.
The above is intended as an exemplification of the various attempts made and approaches taken in order to effectuate a quality splice between at least two fiber optic cables. Although more or less effective, these techniques have specific drawbacks; in particular, specialized and cumbersome tools are often required to perform a simple splicing task.
U.S. Patent application Ser. No. 268,462, "Fiber Optic Ferrule Crimp", filed May 29, 1981 discloses a ferrule crimp for use in conjunction with the splices such as those referred to above. The ferrule comprises an elastomeric insert having a substantially axially aligned bore designed to accommodate variously configured fiber optic cables. A deformable sleeve surrounds the insert so that when a predetermined length of cable has been extended through the insert the sleeve may be crimped, thereby fixing the ferrule positon with respect to the end of the cable. Subsequently, a housing, preferably one such as embodied by the subject invention, may be closed around a pair of such ferrules so arranged in order to form a compression loop in the cables thereby maintaining an end-to-end abutment of the cables.